Method of and means for calibrating electric meters.



O. T. BLATHY.

METHOD OF AND MEANS FOR CALIBRATING ELECTRIC METERS.

APPLICATION FILED SEPT. 7. 1912.

1,160,567. Patented Nov. 16, 1915.

2 SHEETS-SHEET l.

Fig.1 Fig.2 Fig.3 Fig 1 0. T. BLATHY.

METHOD OF AND MEANS FOR CALIBRATING ELECTRIC METERS.

APPLICATION FILED SEPT. 7. I912- Patented Nov. 16, 1915.

2 SHEETS-SHEET 2.

OTTO TITUS BLATHY, OF BUDAPEST, AUSTRIA-HUNGARY.

METHOD OF AND MEANS FOR CALIBRATING ELECTRIC METERS.

Specification of Letters Patent.

Patented Nov. 16, 1915.

Application filed September 7, 1912. Serial No. 719,060.

To all whom it may concern:

Be it known that I, ()TTo TrrUs Bin-(THY, a subject of the King ofHungary, residing in Budapest, in the Kingdom of Hungary, have inventednew and useful Improvements in Methods of and Means for CalibratingElectric Meters; and I do hereby declare the following to be a full,clear, and exact description of the same.

It has heretofore been the practice in the calibration of electricmeters to alter the electro-dynamic braking effect procured by theaction of the magnetism of a steel or permanent magnet upon a brake diskof conducting material by adjusting the brake magnet with respect to thedisk or by adjusting an armature for the magnet, such armature forming amagnetic shunt for the field of the brake magnet, such field shuntingarmature arranged on or in front of the limbs of the brake magnet. Thesemethods of calibration however involve the expenditure of considerabletime and labor, inasmuchv as more than one adjustment of the parts withsubsequent testing or comparison with a standard meter is necessarybefore correct calibration is attained. This time and labor adds to thecost of the correctly calibrated meter. And when a micrometer screw isprovided for affording such an adjustment during calibration the cost ofthe meter is increased and is not compensated for or outweighed by, thesimplification of adjustment resulting from the employment of themicrometer screw.

By my invention, however,correct calibration of a meter or series ofmeters can be effected by a single comparison of each meter with astandard meter accompanied by a simple efi'ort or movement of the handand without recourse to any adjusting apparatus or structure in themeter, with the result that the calibration is greatly'simplitied andthe ultimate cost of production of a calibrated meter is diminishedbecause of saving of this time and labor and the avoidance of adjustingstructure.

According to my invention, I provide in each of the uncalibrated metersa braking magnet producing a somewhat stronger field than is ultimatelynecessary for the braking for securing correct calibration. I comparethe meter with a standard meter and determine by the comparison how muchtoo slowly the meter runs. I then apply magnet field shunting pieces ofpredetermined dimensions and shunting effect to the brake magnet toweaken the field of the magnet through which the disk moves to a degreeust sutlicient to increase the speed of the meter to correspond exactlywiththe standa rd meter.

By my invention a retardation as great as 20 per cent. below the'correctspeed can be compensated for with certainty by the application of thesefield shunting pieces, each of a previously known or predeterminedshunting effect. And by preference I employ magnets which, beforecalibration, are, for example, 5 per cent. stronger than necessar toproduce the correct bra-king effect. The field shunting pieces areproduced in large numbers and of different dimensions, and when appliedto the braking magnet produce a predetermined weakening of the magneticfield. in proportion to their dimensions. The dimensions of thedifferent shunting pieces are selected in such manner that within thelimits of the retardation to be corrected, the necessary correction canbe effected by steps or increments of, for example, one quarter of oneper cent. The

shunting pieces are sorted out and all those of a given dimension orshunting effect are kept together. These shunting pieces are allpreferably of the same length but of different cross sectional areas, asby stamping them out of plates of different-thicknesses or cutting themfrom wires of different diameters, so that they may be sorted accordingto their weights, as by means of automatic scales.

The calibration according to my invention is practised as follows: Aseries of meters to be calibrated are connected 1n circuit in the usualmanner with a standard meter,

the speed of the meter to the correct-value is or are applied to thebrake magnet, as by placing it or them across the poles of the magnet.For the production of the field shunting pieces a metal or an alloyhaving relatively low permeability is preferably employed to the endthat slight yariations in the small dimensions of the shunting piecessuch as are unavoidable when sorting shown in Fig. 10.

may not injuriously affect the accuracy required in the calibration.These field shunting or armature pieces may conveniently be producedfrom pure nickel, since this metal can be obtained commercially of thenecessary uniformity in its magnetic properties that accuracy 1s assuredeven when they are manufactured wholesale.

My invention resides in the method of and means for effectingcalibration of meters.

For an illustration of my method of and means for effecting thecalibration, reference may be had to the accompanying drawings, inwhich:

Figure 1 illustrates one form a field shuntmg or armature piece maytake. Fig. 2 shows a modified form. Fig. 3 shows a further modifiedform. Fig. 4 shows a front view of the form shown in Fig. 3. Fig. 5 is aplan view showing braking magnet and disk with a shunting piece such asshown in Fig. 1 applied to the magnet. Fig. 6 shows in perspective thestructure illustrated in Fig. 5. Fig. 7 shows a brake magnet and disk inperspective with a shunting piece such as shown in Figs. 3 and 4 appliedto the magnet, together with means for holding the shunting piece inposition. Fig. 8 shows in top plan view a braking magnet with shuntingpieces applied thereto in another Way. Fig. 9 is a side elevation of thestructure shown in Fig. 8. Fig. 10 is a top plan view of a brake magnethaving applied thereto shunting pieces disposed in holes in the poles ofthe magnet. Fig. 11' is a side elevation, partly in section, of thestructure Referring to Fig. 1, the armature piece or field shuntingpiece a is formed out of a thin plate or metal bent at right angles andhavmg end portions 6 bent down at right angles to the sides. This pieceis applied as lndicated in Figs. 5 and 6 to the corners f of the polesof the brake magnet m within whose magnetic field is disposed the disk Ssecured to the meter shaft for retarding it. The poles of the magnet m,stand clear of or extend eyond the edge of the disk S and the piece a isso applied to the magnet poles that the side portlons of the piece a areattracted to and adhere to the surfaces 0 of the magnet, While the endportions I), b of the shunting piece a form abutments resting on theupper and lower horizontal surfaces of the magnet poles and so preventsliding or displacement of the piece a, the attraction of the magnet onthe piece a being suflicient to hold it in position.

The armature pieces or shunting pieces which serve to compensate for thevarying retardation may differ from one another either in gage of theplate used or in breadth, that is to say, they vary in their crosssectional area; or in certain cases they may differ from each other inmagnetic permevided with markings (see the mark 2 in Figs. 1 and 6)which indicate the amount of acceleration they will effect when appliedto the magnet.

As shown' in Fig. 2, the shoulders g are provided and serve to preventlongitudinal sliding of the piece.

As indicated in Figs. 3 and 4, holes k may be stamped out of the piecesfor the purpose or reducing the cross sectional area, and therebyreducing the shunting effect of comparatively wide armature or shuntingpieces. When such a piece as illustrated in Figs. 3 and 4 is employed orpieces similar thereto, a spring It may bear against the piece, or anyother suitable means employed to prevent its falling off or displacementdue to jarring or the like.

his to be understood that the forms of structure illustrated in theaccompanying drawings serve as examples only, and that the armaturepieces or shunting pieces may vary in their form in many ways withoutdeparting from the scope and spirit of my invention.

Instead of employing different armature pieces for correcting differentamounts of retardation, a greater or lesser number of armature piecesmay be applied to the magnet according to the amount of retardation tocorrect. Thus, as illustrated in Figs. 8 and 9, a plurality of shuntingpieces a, for example nickel wires, are applied across the poles, of themagnet m, the wires being held by the attraction of the magnet. A-memhera of non-magnetic material may intervene between the wires a and thepoles of the magnet. In the case of Figs. 10 and 11, the holes of themagnet m are bored near the pole corners which stand clear of thebraking disk, to form the holes 0, the hole 0 in the lower limbextending only partially therethrough as indicated in Fig. 11. Thearmature pieces a, as of nickel wire, are placed in these holes, andheld there by magnetic attraction. In order to further secure thesewires a spring 9 pivoted on screw 7) may be provided to extend acrossthe hole 0 in the upper limb after the wires have been inserted.

Suppose the meter requires, upon comparison with the standard meter, anacceleration of 2 per cent. As soon as this is determined, 1n the wellknown manner, the

production which is also reduced in that no dditional structure withinthe meter is re- W Or upon omparison with the standard meter it beingcent. is required, the calibrater may apply,

'- s indicated in Figs. 8 to 11 inclusive, six

redetermined to have an accelerating efi'ect one quarter of one percent. Having applied these six pieces he knows that his eter iscorrectly calibrated and he need not again'compare it with the standardmeter.

" Obviously what has been said of one meter, is true of a series ofmeters which Vhat I claim is:. g 1. The method of calibrating anelectric meter governed by electro-dynamic braking,

tion of said meter on comparison with a standard meter, and thereafterweakening the magnetic field of the electro-dynamic braking system byplacing on the magnet of said field in fixed relation therewith a pieceor pieces forming a shunt path or paths of previously determinedaccelerating effect, whereby said meter is accelerated to correct speed.

2. The method of calibrating an electric meter governed byelectro-dynamic braking, which consists in determining the retarda tionof said meter on comparison with a standard meter, and thereafterintroducing into the magnetic field of the electro-dynamic brakingsystem in fixed relation to the magnet thereof a magnetically permeablepiece or pieces having previously determined '5 weakening effect uponsaid magnetic field, '7 whereby said meter is at once accelerated a tothe correct speed.

3. The method of calibrating an electric meter governed byelectro-dynamic braking, which consists in determining the retardationof said meter on comparison with a standard meter, and thereafterweakening the magnetic field of the electro-dynamic braking system byshunting said magnetic field through a path or paths Without variableair gap or gaps and of previously determined accelerating efi'ect,whereby said meter is at once accelerated to correct speed ard meter.

1. The method of calibrating an electric meter governed byelectro-dynamic braking, which consists in determining the retardationof said meter on comparison with a standard meter, and thereafterintroducing into the magnetic field of the electro-dynamic brakingsystem a magnetically permeable piece or pieces in fixed relation and incontact with the magnet poles and having previously determined weakeningeffect upon said magnetic field, whereby said meter is c uetermined thatan acceleration of 1.5 per Which consists in determining the retarda-,

' without further comparison with said standi as at once accelerated tocorrect speed without further comparison with said standard meter.

5. The combinationwith a meter braking magnet and disk, of a magnetshunting piece of previously determined field weakening efi'ect appliedin fixed position to said magnet.

6. The comination with a meter braking magnet and disk, of a magnetshunting piece of previously determined field weakening effect appliedupon the poles of said magnet and out of the path of said disk.

7. The combination with a meter braking magnet and disk, of a magnetshunting piece of previously determined field weakening effect ofmaterial of lower permeability than that of iron applied upon the polesof magnet.

8. The combination with a meter braking magnet and disk, of a magnetshunting piece of previously determined field weakening effect ofmaterial of lower permeability than that of iron applied in contact withthe poles 3f 1said magnet and out of the path of said 9. The combinationwith a meter braking magnet and disk, of a nickel magnet shunting pieceof previously determined field weakening effect applied upon the polesof said magnet.

10. The combination with a meter braking magnet and disk, said magnethaving pole corners standing free of said, disk, and a magnet shuntingpiece consisting of an angle plate applied to said magnet at said polecorners.

11. The combination with a meter braking magnet and disk, of a pluralityof magnet shun-ting pieces applied to said magnet, each of said pieceshaving previously determined field weakening efi'ect.

12. The method of calibrating an electric meter governed byelectro-dynamic braking, which consists in making a single comparison ofsaid meter with a standard meter, determining fro-m said comparison theretardation of said meter, and thereafter weakening the magnetic fieldof the electro-dy- .namic braking system by applying to the magnet ofsaid system and in fixed relation to said magnet a piece or piecesforming a path or paths having previously determined accelerating effectequal to that necessary to bring said electric meter up to correctspeed.

13. The method of calibrating an electric meter governed byelectro-dynamic braking, which consists in determining the retardationof said meter on asingle comparison with a standard meter, providingfield shunting pieces of previously determined field weakening power,introducing one or more of said pieces into the field of theelectrodynamic braking system in fixed relation to celerates said meterto correct speed.

14. The combination with a meter braking system comprising a disk and amagnet initially producing a field co-acting with said disk to cause themeter to run below desired speed, of a field shunting piece applied toand in fixed relation with said magnet and having a previouslydetermined field weakening effect such as to bring the speed of themeter up to correct value.

15. The combination with a meter braking magnet and disk, of a magnetshunting piece consisting of an angle plate having faces substantiallyparallel with and in fixed relation with the facesof a pole of saidmagnet.

16. The combination with a meter braking magnet and disk, of a magnetshunting piece consisting of an angle plate applied to the poles of saidmagnet, said plate having an abutment preventing displacement .of saidlate. p 17. The method of calibrating an electric meter governed by anelectro-dynamic braking system comprising a, normally too powerfulmagnet'and a conductor movable with respect thereto, which consists indetermining the retardation of said meter, and thereafter placinginfixed relation on said ma et a shunting piece or pieces ofpredetermmed field weakening efi'ect, whereby the effect of said brakingsystem is at once reduced to correct amount.

In testimony whereof, Ihave signed my name to this specification in thepresence of two subscribing Witnesses.

-OTTO TITUS BLATHY.

Witnesses: v

HUGH KEMEING, JoHN 'J. 'RoU'rs.

